Coated fabric



Patented Nov. 30, 1 943 V l Tl' -D STATES PATENT. OFFICE I j 2.335.739 ii COATED FABRIC Merle H. Chamberlin, Newbmh Sig-11 i to E. I. du Pont deNemours & Company; Wil-v I i. mington, Del., acorporation of Delaware NoDrawing.

Application January 31, 1942, Serial No. 428,979

16 Claims. (Cl. 117-46) This invention relates to nitrocellulose coatedsheets, including non-woven paper sheets and woven fabric sheetawhichcontain a material which will discolor nitrocellulose.

In my copending application Ser. No. 416,601, filed-October 25,1941,there is disclosed and claimed a stain resistant'nitro'cellulose coatedfabric which is surfaced .with a layer of eithercelluloseacetobutyrate'or cellulose acetopropionate. This material isresistant to staining by colored cosmetica foodstufis, etc.

In" the coated fabric industry the base fabric,

usually cloth or, paperJiS often dyed a color approximately the color ofthe coating which is to-besubsequently applied; The dyes employed arewater-solubleanddo-notbleed when contacted with organic solvents whichare employed in cellulose derivative compositions." When a 'paper' baseis made from reclaimed rags which are usuallydyed, occasionally smallquantities of anoil or spirit-soluble-dyefwill be carried over to thepaper- -base. When a n'itrocellulose containingcompo sitioii appliedover a base material containingonly tracs df oil or" spirit soluble, thedyestuff willbleed -'1'1p through thenitrocellulose coatingandthedyecolor-will appear on the surface of the coating, thus marring theappearance of the'finished'product. --This'is extremely objec-'tionable'wliere the nitrocellulosecoating is of a shade lighterthan'thedyestuif color. I

Also in'the dyeing of fabrics with water soluble dyesto be subsequentlycoated with organic solutions of nitrocellulose compositions the dyesemployed frequently become contaminated with traces of oil or"spirit'soluble-dyestufis' which will remain on the fabric after dyeingand will bleed up through the nitrocellulose coating.

In the case of paper made from reclaimed dyed rags, it is not practicalto extract the oil or spirit soluble dyestufl's before converting therags into paper sheets and, therefore, such'paper has not plasticizerswillalso discolor lightfcolored nitrocellulose coatings applied oversuch a paper base.-

This invention hasasa primaryv object, the, provision of a'simple andeconomical'method of preventing the discoloration of, nitrocellulosecoatings applied overuapaper oriabric bases containing a materialwhichwill discolor nitrocellulose, and doesnot'requirewany procedure'or'apparatus other than thatnowused-inithe coated fabric and paperindustry. objective, as well as other important but subsidiaryobjectives will become readily-apparent to-' those skilled in the art-asthe description of the invention pr'o'ceeds";

These objects are accomplished by *afpplyingfa' barrier coating of acellulose acetopropionat'e or cellulose acetobutyrate ai'reuy ov'erthefabric or paper base containing either spirit-broilsoluble dyestufl,rubber antioxidants .or; -a-bituminous plasticizer, and subsequentlyapplying a nitrocellulose coatin'g over the barrier coat. N Thebarriercoating will not permit the" migration of'the nitrocellulose stainingina'terial'up tli'rou gfli 'fto' found widespread -use as a base fornitrocellulose coatings. These papers have been confined to blackcoatings which would not show the discoloration resulting from thecontaminating dye- The paper stocks suitable for coating with thenitrocellulose.

The following description of the prefe bodiment is given by the "way'o'fillustration and not limitation; it beingund'er's'tood that theinvention is not to belimited to this pre ferred'em- EXAMBLEI A wovenfabric pound per 53 inch width and having a sateen weave was dyedwith-an oil or spiritsoluble dyestuif. A plurality of coats of acellulose acetopropionate coating of the following approximatecomposition was applied by means of a doctor knife. Base coatingcomposition Per cent by weight Cellulose acetopropionatenu 18.75 Ethylphthallyl ethyl glycollate 6.25 Ethyl mh 37.50 Ethyl aceta 37.50

Sufiicient coats of the above composition were applied to deposit 2ounces per yard per inch width of the non-volatile components. The

method of preparing the above composition is well known in the art andfurther detailed description does not appear to be necessary. The

volatile solvents were expelled between each successive coat of thecomposition by passing the material through a heated chamber.

The material was then given a plurality of coats of the followingcomposition:

Surface coating composition Per cent by weight Cellulose nitrate 14.10

White pigment 14.57 Castor oil 24.76 Ethyl alcohol 23.28 Ethyl aceta23.29

The volatile solvents were expelled by passing the coated fabric througha heated chamber. The surface coating firmly anchored to the celluloseacetopropionate coating. Sufilcient surface coating composition wasapplied to deposit approximately 15 ounces of non-volatile compo- .nentsper yard for 50 inch width. The coated EXAMPLE H The followingcomposition has been-found satisfactory as barrier coats to be applieddirectly over a fabric or paper base containing an oil or spirit solubledyestufl which is subsequently over coated with conventional plasticizednitrocellulose compositions:

Base coating composition Per cent by weight Cellulose acetobutyrate18.75 Mixture of orthoand para-toluene ethyl sulfonamides 6.25 Ethylalcohol 37.50 Ethyl ace 37.50

Exemma III A film deposited from the following composition is asatisfactory barrier to the passage of oil or spirit soluble dyestufl,rubber antioxidants and bituminous materials contained in paper orfabric sheet'material:

Bas'e coating composition Per centby weight Cellulose acetobutyrate17.90

Zinc oxide 13.84 Mixture of orthoand para-toluene ethyl.

sulfonamides 6.92

Ethyl alcohol 30.67

Ethyl acetate 30.67

While in the preferred embodiment of this invention the barrier coat ofcellulose acetopropionate or cellulose acetobutyrate is applied directlyover the base material containing either an oil soluble dyestuff, rubberantioxidant or a bituminous material, it may be sandwiched in betweentwo layers of cellulose nitrate coatings. This is particularlyadvantageous in commercial production when the cellulose nitrate coatingis applied over a dyed cotton fabric or paper base in which the dyeforthe fabric or paper dye was unknowingly contaminated with oil solubleor spirit soluble dyestufi and was not detected until a portion of thenitrocellulose coating had been 7 applied. A barrier coat of either thecellulose acetopropionate or cellulose acetobutyrate com-, position maybe applied over the discolored nitrocellulose coating and a suflicientcoating of additional nitrocellulose com'positon applied over theintermediate barrier coat to hide discolored areas since the barriercoat is usually unpigmented and does not conceal the stained areas.

In the preferred examples the barrier coat is a mixed ester ofcellulose, such as cellulose acetobutyrate and celluloseacetopropionate.

. It is also to be understood if the base material containing the oil orspirit soluble dyestuif is to be coated on each side, it is necessary toapply the barrier coat on each side of the base material. Also if thesheet base material containing a nitrocellulose staining material is tobe coated on one side only andto be stored for any length -of time inroll form where the coating is in direct contact with the uncoated sideof the base material, it is desirable to apply a barrier coat on eachside of the base material in order to seal in the nitrocellulosestaining material and prevent contact with the nitrocellulose coating.

While the invention has been described with respect to a specificconstruction of a coated 'fabric, it will be readily-apparent to thoseskilled in the art that the invention can be utilized with any pyroxylincoated fabric construction or pyroxylin coated paper. There is nolimitation to be placed upon the nitrocellulose composition which isapplied over the barrier coat in accordance'with the teachings of thisinvention.

The plasticizer for the cellulose acetopropi onate or celluloseacetobutyrate is preferably one which does not have an afinity for theoil or spirit soluble dyestuffs, commonly used in the dyeingof fabricsor paper to form the baseof pyroxylin coated sheets. Plasticizers forthecellulose acetopropionate or cellulose acetobutyrate, other thanthose mentioned in the examples,

which ehave been found to besatisfactory for I the purpose of thisinvention are triethylene glycol dihexoate, dibutyl phthalate, dibutyltartrate, triethylene glycol dicaprylate, tricresyl phosphate, tributylphosphate and the dibutyl ester of sebacic acid.

It has been found that the resistance of the barrier coat to the passageof the nitrocellulose staining material is in proportion to the amountof plasticizer content present. ,It has been discovered that if theplasticizer content of the barrier coat is increased beyond 65% of thetotal amount of non-volatile components of the barrier coat, that it isnot sufllciently resistant to the oil or spirit soluble dyestufl.

' In the preferred embodiment the nitrocellulose overcoating contains anoil or softener and a pigment. It has been found that the oil orspiritsoluble dyestuffs, rubber, antioxidants, and bituminous plasticizerswill discolor unpigmented, plasticized nitrocellulose films. Also thesematerials will discolor unpigmented, and unpla-sticized nitrocellulosefilms.

This invention will find great utility in the field of nitrocellulosecoated fabrics and papers in using base materials which unknowinglybecome contaminated during the dyeing process with spirit or oil solubledyestuffs which otherwise could only be used as a base for very dark orblack shades. Also the invention will find reat use in coating paperscontaining nitrocel lulose discoloring materials such as rubberantioxidants, and bituminous materials. Where the dyed base material isunknowingly contaminated with oil soluble'dyestufi, it is not normallyencountered until the first one or two coats of the cellulose derivativeare applied at which time a layer of the barrier coat can be appliedover the discolored coating and then the cellulose derivative coatingapplied over the barrier coat.

An advantage of this invention is that it allows the use of paper basematerial made from reclaimed rags which contains 011 soluble dyestufisfdr light colored pyroxylin coatings. A further advantage is that itpermits the use of water soluble dyestufis which have becomecontaminated with oil or spirit soluble dyestufl for dyeing paper orfabric sheets which are to be subsequently coated with compositionscontaining organic solvents in which case the oil or spirit solubledyestuflf does not bleed up to the surface of the coating.

It is apparent that many widely different embodiments of this inventionmay be made without departing from the spirit and scope thereof, andtherefore, it is not intended to be limited except as indicated in theappended claims.

I claim:

1. A base material containing a nitrocellulose discoloring agent saidbase material having superposed on-at least oneside thereof a coatin ofa mixed cellulose ester of a plurality of lower aliphatic acids, saidmixed ester being characterized by its resistance to coloring by saidagent and an overcoating of a nitrocellulose composition, saidnitrocellulose composition being characterized in that it is susceptibleto coloring by said agent. v 2. The product of claim 1 in which themixed cellulose ester comprises cellulose acetopropionate.

3. The product ofclaim 1 in which the mixed cellulose ester iscelluloseacetobutyrate.

4. A dyed fabric base material containing a ester of cellulose comprisescellulose acetobutyrate.

7. A dyed paper base material containing a nitrocellulose discoloringagent having superposed on at least one side thereof a coating of mixedcellulose ester of a plurality of lower aliphatic acids, said mixedester being characterized by its resistance to color bysaid agentnitrocellulose discoloring agent said base material having superposed onat least one side thereof a coating of a mixed cellulose'ester of aplurality of lower aliphatic acids, said mixed ester being characterizedby its resistance to coloring by said agent and an overcoating 01' anitrocellulose composition, said nitrocellulose composition beingcharacterized in that it is susceptible to color by said agent.

5. The product of claim 4 in which the mixed ester comprises celluloseacetoproplonate.

6. The product of claim. in which the mixed and an overcoating of anitrocellulose composition, said nitrocellulose composition beingcharacterized in that it is susceptible to color by said agent.

8. The product of claim v'7 in which the mixed ester of cellulosecomprises cellulose acetopropionate. v I

9. The product of claim 7 in which the mixed ester of cellulosecomprises cellulose acetobutyrate.

10. A dyed sheet base material containing a nitrocellulose discoloringagent said base ma- ;terial having superposed on both sides thereof acoating of a mixed cellulose ester of a plurality of lower aliphaticacids, said mixed ester being characterized by its resistance tocoloring by said agent and an overcoatlng of a nitrocellulosecomposition, said nitrocellulose composition being characterized in thatit is susceptible to coloring by said agent.

11. The product of claim :10 in which the mixed cellulose estercomprises cellulose acetopropionate.

12. The product of claim 10 in which the mixed cellulose ester comprisescellulose acetobutyrate.

13. A dyed sheet base material containing a nitrocellulose discoloringagent said base material having a first coating of nitrocelluloseapplied directly thereto, a second coating of a plasticized celluloseester of mixed lower aliphatic acids composition superposed on the firstmentioned coating, 9. third coating of nitrocellulose applied over saidsecond coating, the said first and third coatings being characterized inI that they are susceptible to coloring by said discoloring agent. I

14. The product or claim 13 in which the 16. The product of claim 13irrwhich the-plasticizer in the mixedester coat is less than per centthereof.

MERLE H.

